TIR is an internet acronym for Today I Remembered or Today I Realized, for when you remember something from the past or have a sudden awareness of something. TIR is similar to TIL (Today I Learned) but often indicates past knowledge or exposure to the information.

TIR an awesome cartoon from my childhood.

TIR how to write the letter "G" in cursive... and that we never used cursive in high school.